Operating mechanism for fire prevention apparatus



Jan. 26, 1932. J. E. COHEN ET AL. '4 1,842,658

OPERATING MECHANISM FOR FIRE PREVENTION APPARATUS Filed June 1, 1928 2 Sheets-Sheet 1 3113-- 2|- LEIG- E f .90 I I/ l M a E; ji j f Z 15 I ATTORNEY.

WITNESSES:

Jam 26, 1932. JQE, COHEN 1,842,658 I OPERATING MECHANISM FOR FIRE PREVENTIQN APPARATUS Filed June 1, 1928 2 Sheets-Sheet 2 firs-- 1! 'WITNESSES: mmvroxs,

. 5 m Ellis Cohen ATTORNEY.

5 Jgz m FunczsAdamg Patented Jan. 26, 1932 earner eerie f .rosnrn Ennis comm Ann 101m FRANCIS ADAMS, or rnrrannarnrn, ranrusynvama,

assronons TO SEN'IRY sunny conrnor. conrom'rron, on PHILADELPHIA, rmm- SYLVANIA, A CORPORATION or nnnawann OPERATING MECHANISM FOR FIRE PREVENTION ABBARATUQ Application filed June 1, 1928. Serial No. cease-a This invention relates to fire prevention apparatus for motion picture projecting inachines, and particularly to novel means for operating the devices of such apparatus.

One of the objects of the invention is to provide for the operation of well-known safety appliance through the medium of photoelectric cells and amplifying tubes.

Another object of the invention is to provide simplified means for operating motion picture machine safety devices,

Another object of the invention is to provide electrical controls for motion picture safety devices to eliminate mechanical controls.

According to the invention, the motion picture machine, which is provided with the usual mechanism for holding the dowser out of light obstructing position, is provided with one or more light sources which normally act upon one or more photo-electric cells when the film is operating properly, and which light sources are, obstructed by the improper operation of the film, whereupon the action of the photo-electric cells reduces the current flowing in an amplifying tube, which in turn operates a mechanism to stop the motor and drop the dowser to obstruct the beam of light passing through the film.

The drawings illustrate an embodiment of the invention and views therein are as follows:

Figure 1 is a fragmentary schematic view of a motion picture projecting machine equipped with the mechanism of the invention.

Figure 2 is a plan view of the upper light box and upper photo-electric cell box showing the pencils of light emanating from the former to the latter and showing the film in section and in its proper position under normal conditions.

Figure 3 is a similar view and shows a modified method of operation directly reverse to the method of operation in Figures 1 and 2. s

Figure 4 is a wiring diagram showing the manner in which safety mechanism of the picture machine is connected for operation. Referring to Figure 1, 6 illustrates the upper reel and 7 the lower reel, 8 the upper nlmlng rolls consisting of idle rolls and sprockets, and 9 the lower filming rolls which also consists of idle rolls and sprockets. 11 shows the upper light box, 12 the lower light box, 13 illustrates the upper photo-electric cell box and 1d the lower photo-electric cell box, and 16 illustrates the in which is contained the relay 17 and an amplifying tube 18. 19 represents the cone on the front I L of the are light housing through which the rays of light are directed through the film for projecting the images thereon, while 21 represents the dowser operating unit and 22 the dowser, The dowser operating unit and mechanism therein form no part of this invention, except insofar as they are operated by the same, and as an illustration of one type which may be used in connection herewith, reference may be had to the co-pending application of John Francis Adams, one of the applicants herein, filed Qctober 12, 1927, Serial Number 225,808.

In its ordinary operation the film 23 of the picture machine is motor-fed from the upper reel 6, through the filming rolls 8, and at the point designated by the numeral 24, the upper loop is formed. The part designated by the numeral 26 passes over the aperture plate of the machine (not shown) and it is at about the center of this length that the images of the film are projected by the rays of the are light (not shown). The film then passes down through the lower filming rolls 9 and has a straight portion 27 extending down to the idle rolls 10 from whence it passes into and is taken up by lower reel 7.

The upper light box 11 is arranged so that pencils of light 28 and 29 are passed obliquely, one on each side of the film, when its loop 24: is normal.

Figure 2 shows the normal condition of the film at the loop and the pencil of light on each side of the same. The view may be said to be taken in the direction of the arrow A. The lower light box is arranged in similar manner with pencils of light 31 and 32 passing obliquely on each side of the straight portion 27 of the film.

The principle of operation will be readily understood when We realize that faulty operation of the film through the filming mechanism will either lengthen or shorten the loop 24 so that it will either be pushed outward or drawn inward, thereby cutting off one or the other of the pencils of light from the photoelectric cells in the box 13. Also, if the film breaks, the broken end would fiy across one of the pencils of light and thereby would momentarily shut off the light from one of the photo-electric cells.

The same condition as that above described will take place across the straight portion of the film 27 if the film should clog or be improperly taken up by the lower reel. The film will move across one of the oblique pencils of light so as to shut ed that particular pencil of light from the corresponding photoelectric cell.

In the same manner if the film should break it will momentarily pass across one of the pencils of light and obstruct it from its photo-electric cell.

Referring now to the wiring diagram Figure 4, we have direct electric current supplied from any suitable source and to the wires designated and The current supply line is supplied with a switch 33. The positive or terminal of the switch is connected by a wire 34 which extends to the contactor of a variable resistance 36 and such resistance is connected by a wire 35 which supplies current to the lights 37 and 38 in the upper light box 11. These lights are in parallel and are connected with the return wire 39 which is connected by the wire 41 to the wire 42 which in turn connects with the negative or terminal of the switch 33. The wire 34 is connected by a wire 43 and this wire is in turn connected by a wire 44 which passes to a suitable resistance 46 and from thence to the filament 47 of an amplifying tube 18.

The return wire 48 from the filament connects with the wire 41 which runs to the negative side of the supply line.

The wire 44 is connected by a wire 49 which passes to the contactor of a variable resistance 51 and a wire 50 extends from said resistance to the coil 52 of the relay switch 17 which has two contacts 54 and 56 and whose armature 57 is adapted to bridge said contacts is normally drawn therefrom by means of a spring 58.

The other end of the coil 52 is connected by a wire 59 which connects to the plate 61 in the amplifying tube 18.

The wire 43 connects with a wire 62 whose one end is connected to the contact 54 and whose other end runs to the motor M. The other side of the motor M is connected by a wire 63 which passes to the contact 64 of a relay 66, and the other contact 67 of said relay is connected by the wire 42 which passes to and connects with the negative terminal of the switch 33.

The contact 56 of the relay 53 is connected by a wire 68 which in turn connects a wire 69 with one terminal of mercury switch 71. The other terminal of the mercury switch 71 is connected by a wire 72 which extends to and is connected to one end of the coil 73 of the relay 66 while the other end of said coil is connected by a wire 74 to the wire 42.

The wire 68 is also connected by a wire 76 to one end of a solenoid 77. The other end of the solenoid is connected by a wire 78 which is connec :ed with a suitable resistance 7 9 and then connects with the wire 63.

A centrifugal switch designated by the numeral 81 is connected across the wires 68 and 78.

The particular style of switch designated by numeral 81 is immaterial, but a switch such as that described in the co-pending application of John Francis Adams, one of the applicants herein and Thomas T. Allen, filed December 13, 1927, Serial Number 239,622, may be employed, and in fact, is designed to beemployed in connection with this mechamsm.

Connecting with the wire 59 is a wire 82 which connects with the grid 83 in one of the photo-electric cells, and the wire 84 is tapped off the wire 82 and connects with the grid 86 of the other photo-electric cell. 7

The plates 87 and 88 are connected in multiple through the wires 89 and 91 and the former of these wires extends to and is connected with the grid 92 in the amplifying tube 18.

So far, the description has been in connection only with the upper light box 11 and photo-electric cell box 13, but the wire 93 and 94 may be tapped off the wires 89 and 82 respectively and connected with the lower photo-electric cells in the box 14. The wires 35 and 39 may also extend to the lights in the lower light box 12.

During the-normal operation of the picture projecting machine, current will pass from the positive terminal of the switch 33 through the wire 34, wire 43 wire 44, wire 49, through the variable resistance 51, through the wire 50 and the coil of the relay 17, thence through the Wire 59 to the plate 61 of the amplifying tube 18. The current will flow across from the plate to the filament 47 and thence downward through the wire 48, the wire 41 and the wire 42 of the negative terminal of the switch 33.

Normally there is a flow of electrons from the filament 47 to the plate 61 of the tube 18 which determines the amount of current which flows from the plate 61 to the filament 47. The grid 92 being connected as it is to the plates 88 and 87 through the wires 89 and 91 will be affected by the flow of current from the grids 83 and 86 which are connected to the positive side of the line through the wire 59, and which passes from the grids 83 and 86 to the plates 88 and 87 respectively.

This action of the photo-electric cells in the box 13 places a positive charge on the grid 92 of the tube 18 thereby increasing the current flow from the plate 61 to the filament 47 in said tube.

During the ordinary operation of the machine and with the pencils of light 28 and 29 acting upon plates 87 and 88 in conjunction with the pencils of light 31 and 32 from the lower light box 12 acting upon the plates of the cells in the box 14:, there is suficient current flowing from the plate 61 to the filament &7 in the tube 18 and, therefore, through the relay coil 52 to hold the armature 57 against the contacts 5e and 56 of the relay switch 53, thereby keeping the motor circuit closed and the solenoid 7 7 energized to hold the dowser 22 in its raised position to permit the are light to extend its beam through the aperture in order to project the images from the film to the screen.

If, however, the film 23 should operate im= properly, or fluctuate from the position shown in Figure 1, it will pass across one or the other of the pencils of light 28 and 29 so as to obstruct one or the other of the same and thus prevent said pencil from being directed onto its respective plate of the, photoelectric cells. Thisobstruction of the light will prevent the flow of electrons from the plate to its respective grid and will thereby prevent the flow of electric current from the grid to the plate.

It will, of course, be understood that the same condition will take place with the straight portion of the film 27 which normally extends between the oblique pencils of light 31 and 32.

The obstruction of any one of the pencils of light 28, 29,- 31 or 32 diminishes the positive charge on the grid 92 of the tube 18, and as the coil 52 on the relay 17 is quite sensitive, the slightly reduced current will sufiiciently lower the magnetic pull thereof, so that the 1 spring 58 may withdraw the armature 57 from the poles 54: and 56 and thereby open the motor circuit. This same action of the relay will de-energize the solenoid 7'? which trips a latch shown and described in the application Serial Number 225,808 above referred to,

so that the dowser unit will operate to permit the dowser 22 to fall by gravity and thereby intercept the beam of light from the arc which extends through the cone 19 during normal operation.

Of course, the switch 81 which is included in the motor circuit is intended to prevent the dowser from being held out of light obstructing position until the motor M attains a predetermined speed, and if at any time the motor operates below that speed, or should stop by reason of the blowing of a fuse or otherwise, the switch will operate to short circuit the solenoid 77 and thus operate the dowser unit in the same manner. However,

electric cell being connected to the function of this centrifugal switch 81 is fully explained in the application Serial Number 239,622 above referred to.

it follows that if pencils of light acting upon photo-electric cells may be used for causing a positive charge upon the grid of the filament 92 of the tube 18, in order to cause sufficient magnetic action in the coil 52 to hold the relay 53 closed, that a reverse condition may be employed which can be understood by reference to Figure 3. If, for instance, the pencil of light referred to in said Figure as 96 was normally extended from a single light box 97 toward a single photoelectric cell in a box 98, and this pencil of light were normally obstructed or interrupted by the film 23, the relay 17 can be so arranged that the armature 57 normally contacts with the contacts 54 and 56, and when the film 23 fluctuates, the pencil of light 96 would be extended onto the plate of the photo-electric cell in the box 98 so as to energize the coil 52 of the relay 53 and thus draw the armature 57 from contact with the contacts 54. and 56.

It is, of course, understood that while the photo-electric cells and their li ht sources have been illustrated and descri ed at certain specific points in the film travel that they may be placed at any point desired with equally good effect.

It is also understood that the photo-electric cells and the vacuum tube herein described are not of themselves new, but are of the standard types and styles used in radio or television work, but their specific application to motion picture work is novel and constitutes the invention herein contained.

It will, of course, be understood that by the use of mirrors and screens the light sources shown in the light boxes 11 and 12 for projecting the pencils of light onto the photoelectric cells may be provided for by the main are which projects the images of the film onto the screen, so that a single light source may be utilized for all purposes.

Of course, the mechanism and the connection of parts as shown by the wiring diagram and herein illustrated may be modified and changed in various ways without departing from the invention herein set forth and hereafter claimed.

ive claim 1. In combination with fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of means including a photo-electric cell, a pencil of light normally adjacent the film loop and adapted to act on said photo-electric cell, an amplifying tube, a relay, the photothe grid of the amplifying tube to vary the normal uniform current therein when the pencil of light is interrupted by the abnormal displacement'of the film, so that the change in current will operate the relay which in turn operates the fire prevention apparatus.

2. In combination with fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of means including a control circuit having a photo-electric cell, an amplifying tube and a relay, a circuit in parallel with said control circuit for supplying a pencil of light adapted to act on said photo-electric cell. the photoelectric cell being connected to the grid of the amplifying tube to vary the normal uniform current therein when the pencil of light is obstructed by the film, so that the change in current will operate the relay which in turn operates the fire prevention apparatus.

3. In combination with fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of means coi'nprising a plurality of photo-electric cells, a plurality of light sources adapted to direct pencils of light onto the plates of said photo-electric cells and on either side of said film, a control circuit having an amplifying tube and a relay in series, the plates of said photo-electric cells being connected to the grid of the amplifying tube so as to vary the current in said control circuit when the film obstructs any of the pencils of light,

whereby the reduced current in said control circuit operates said relay which in turn crates the fire prevention apparatus.

4. In combination with fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of a pencil of light adjacent the normal loop of the film, a control circuit for the apparatus including a photo-electric cell upon which said pencil is adapted to act and which, when the film loop is displaced abnormally and so as to interrupt said pencil, will operate said apparatus.

5. In combination with fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of a pencil of light disposed on each side of the normal loop of the film, a control circuit for the apparatus including a photo-electric cell upon WhlCh said pencils are adapted to act and which, when the film loop is displaced abnormally and so as to interrupt either of said pencils, will operate said apparatus.

In combination with fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of a pencil of light'adjacent the normal loop of the film, a control circuit for the apparatus including a photo-electric cell, an amplifying tube and a relay, the interruption of the pencil of light by the abnormal displacement of the film loop being adapted to cause the light sensitive devices to operate the relay, break the circuit and thereby operate the apparatus.

7. In combination with. fire prevention apparatus for a motion picture machine which has a light source for projecting the images of a film and means for feeding the film, of a pencil of light adjacent the normal loop of the film, a control circuit for the apparatus including a photo-electric cell and an amplifying tube and relay in series and having a normally constant current, which said current is varied by the interruption of the pencil of light caused by the abnormal displacement of the film loop, whereby the relay opens the circuit and operates the apparatus.

8. In combination with fire prevention apparatus for a chine which has a light source for projecting the images of a film and means for feeding the film, the means comprising an electric circuit having a photo-electric cell and a light source for energizing same, an amplifying tube, and a relay in said circuit, said fire prevention device being operable through the medium of the amplifying tube and relay when said fihn is fed in a manner to interrupt the passage of light to the photo-electric cell.

In testimony whereof we have signed our names to this specification.

JOSEPH ELLIS COHEN. JOHN FRANCIS ADAMS.

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